1. Field of the Invention
This invention relates to a slide filing plate, and more particularly to a slide filing plate having a translucent or transparent protective membrane, which membrane protects slide film carried by the filing plate in such a manner that the pictures of the slides can be projected without removing the slides from the filing plate and without being significantly disturbed by the presence of the membrane.
What is meant by the words "slide film" here refers to various kinds of films carrying pictures which are to be projected onto a screen by a suitable projector. Accordingly, the slide film includes conventional color slide film, microfilm, and other films which are used for storing informations.
2. Description of the Prior Art
A slide holding plate (to be referred to as "the slide filing plate", hereinafter) has been used for orderly holding or filing a plurality of mounted slide film in a common plane in such a manner that all the slide film can be viewed simultaneously. Such known slide filing plate is made by shaping cardboard or a plastic sheet material into a filing sheet having a plurality of pockets for receiving individual slides therein, respectively.
Some of the conventional slide filing plates have transparent diffusion membranes disposed at each of the slide-receiving pockets for protecting the emulsion surface of the slide film against mechanical contact with foreign matter and for facilitating the viewing of the picture of the slide film by diffused light through the diffusion membrane. Such slide filing plate with diffusion membranes is highly suitable for safe storage of slide film in an orderly fashion, but if one tries to project the picture of the slide film by a suitable projector, the slides must be removed from the filing plate one by one for placing it in the projector and then the slides must be returned to the filing plate again one by one upon completion of the projection. This removing and returning of the slides relative to the filing plate for the projecting operation is cumbersome.
To mitigate such difficulty, it has been proposed to eliminate the diffusion membranes from the pockets of the filing plate. If, however, the diffusion membranes are eliminated, the emulsion surfaces of the slide film are directly exposed to the outside air, so that the risk of damage by mechanical contact with foreign matter is increased, so that the general level of protection of the slide film is reduced. Furthermore, without the diffusion membrane, it becomes rather difficult to simultaneously view all the pictures of the slides carried by the filing plate.
When one tries to project the picture of a slide, which is carried by the filing plate with the diffusion membranes, in the state as placed on the filing plate, enlarged images of particles and veins on the diffusion membrane, intrinsic or extrinsic, are superposed on the desired image of the slide picture. Thus, the quality of the projected image of the slide picture becomes very poor, so that, in the case of filing plates with the diffusion membranes, it is not practical to project the slide pictures without removing the slides from the filing plate.
In short, there are two types of known slide filing plates, one type being suitable for safe storage of the slide films and the other type being suitable for projecting the slide pictures without removing them from the filing plate. However, there has not been any slide filing plate which simultaneously provides safe protection of slides for orderly storage and easy projection of slides by a projector without necessitating the removal of the individual slides from the filing plate.
Therefore, an object of the present invention is to mitigate the aforesaid difficulties of conventional slide filing plates by providing a novel slide filing plate.